My ph meters keep showing different amounts and don't seem to respond to ph changes, but they always read the reference solutions correctly.

[Olderfart]

pH probes use ion selective membranes to measure the voltage caused by the concentration of hydrogen ions, and hydrogen ions only, on either side of the membrane. They are simply volt meters whose voltage reading is displayed in corresponding pH units. The probes are the difficult bit, the electrics are dead simple by comparison. The reason that the higher end meters require storage in a liquid storage solution, usually a solution of KCL, is that the selective membranes used in the pH probe can be damaged by drying out, or by storage in solutions which are osmotically or chemically inappropriate. KCL storage solutions, as I understand it, are designed to closely match the osmotic and chemical concentrations on either side of the selective membranes, which prevents damage caused either by drying out, or by fatigue (my word) caused by long term exposure to high osmotic or chemical differential across the test membrane. All the high end meters require this sort of care in storage, and I see no reason to expect that cheaper probes are less sensitive to the same kind of damage.

Or so goes my understanding, I would welcome correction by someone more familiar with the chemistry than I am. For anyone wanting to explore this issue further, Wikipedia has a reasonable discussion here: https://en.wikipedia.org/wiki/PH_meter#Principle_of_operation

My experience with actual meters is limited, but here it is. I initially bought a cheap pen off Amazon after finding the color of the test liquid kit to be a pain to interpret. The meter worked like a hot damn for several days, was more than accurate enough, and consistently stayed close to pH of test solutions when tested for calibration. I was a happy camper thinking how I saved big bucks. Then on about day 5 or so, I forgot to put the cap back on for just an hour or so, which presumably allowed the probe to dry out. Immediately after, calibration went to hell, and by 24 hours or so later, the meter would not work at all. I sent the meter back for a refund, and applied the refund to an Apera, which worked flawlessly for the rest of the grow.

Based on my experience and homework, I recommend buying an Apera in the first place, buying some KCL powder to mix storage solution as specified by Apera (I can't remember whether it is 3 or 4 molar), and storing the probe in a capful of solution after each use. If you do buy a cheap meter, do not let the probe dry out even briefly, and store it in a capful of KCL solution. The cheap meters seem to seldom if ever recommend a KCL storage concentration, but just choosing one of those recommended by Apera or other manufacturers would likely still be better than nothing. DO NOT store in pure water, that will bugger the membrane up as badly as drying it out. If you do not have and cannot get KCL storage solution, many manufacturers suggest storage in the ~pH4 calibration solution as an alternative, so that may be the best alternative until KCL storage solution is available.

As always, I take zero offense to being corrected by someone who knows more about this than I do.

 

[GinFizzLuv]

If I want a “buy it for life” ph pen what price range am I looking? Are the $60-70 Apera ones good enough? Also is it worth getting one of the 5-in-1 pens?

 

[Olderfart]

If I want a “buy it for life” ph pen what price range am I looking? Are the $60-70 Apera ones good enough? Also is it worth getting one of the 5-in-1 pens?

Dunno about the buy for life bit, but the Apera I purchased for ~~$100Cdn as I recall has a replaceable probe if needed. It is the probe sensor that is the problem with longevity and reliability with these meters, the electronics should last for many years of use at least they should in waterproof units like the Apera. The cheapies are not waterproof, drop them in your nute solution once, and they are dead. Even if the Apera probe sensor had to be replaced annually, the costs would be reasonable compared to the loss of a grow due to pH screwups. As I recall, a new probe is not much costlier than a couple of the cheap pens, or for that matter four or so cannabis seeds. I pretty much guarantee that an Apera probe will outperform and outlast a couple cheap pens.

If I get another grow going next winter, I will report on how my Apera has made out in long term storage in KCL solution. In the meantime, I strongly recommend purchase of an Apera rather than a cheapie, or if you just can't part with the cash, just stick with the pH drops - if used carefully, they should keep you out of trouble better than a buggered pen will. And they never just die and leave you unable to test pH. If you have drops left, you know that you can test pH effectively. Having drops as a backup probably makes sense regardless of which meter you buy.

Good luck with pH adventures, and stay safe peeps.

 

[Bantersaurus]

pH probes use ion selective membranes to measure the voltage caused by the concentration of hydrogen ions, and hydrogen ions only, on either side of the membrane. They are simply volt meters whose voltage reading is displayed in corresponding pH units. The probes are the difficult bit, the electrics are dead simple by comparison. The reason that the higher end meters require storage in a liquid storage solution, usually a solution of KCL, is that the selective membranes used in the pH probe can be damaged by drying out, or by storage in solutions which are osmotically or chemically inappropriate. KCL storage solutions, as I understand it, are designed to closely match the osmotic and chemical concentrations on either side of the selective membranes, which prevents damage caused either by drying out, or by fatigue (my word) caused by long term exposure to high osmotic or chemical differential across the test membrane. All the high end meters require this sort of care in storage, and I see no reason to expect that cheaper probes are less sensitive to the same kind of damage.

Or so goes my understanding, I would welcome correction by someone more familiar with the chemistry than I am. For anyone wanting to explore this issue further, Wikipedia has a reasonable discussion here: https://en.wikipedia.org/wiki/PH_meter#Principle_of_operation

My experience with actual meters is limited, but here it is. I initially bought a cheap pen off Amazon after finding the color of the test liquid kit to be a pain to interpret. The meter worked like a hot damn for several days, was more than accurate enough, and consistently stayed close to pH of test solutions when tested for calibration. I was a happy camper thinking how I saved big bucks. Then on about day 5 or so, I forgot to put the cap back on for just an hour or so, which presumably allowed the probe to dry out. Immediately after, calibration went to hell, and by 24 hours or so later, the meter would not work at all. I sent the meter back for a refund, and applied the refund to an Apera, which worked flawlessly for the rest of the grow.

Based on my experience and homework, I recommend buying an Apera in the first place, buying some KCL powder to mix storage solution as specified by Apera (I can't remember whether it is 3 or 4 molar), and storing the probe in a capful of solution after each use. If you do buy a cheap meter, do not let the probe dry out even briefly, and store it in a capful of KCL solution. The cheap meters seem to seldom if ever recommend a KCL storage concentration, but just choosing one of those recommended by Apera or other manufacturers would likely still be better than nothing. DO NOT store in pure water, that will bugger the membrane up as badly as drying it out. If you do not have and cannot get KCL storage solution, many manufacturers suggest storage in the ~pH4 calibration solution as an alternative, so that may be the best alternative until KCL storage solution is available.

As always, I take zero offense to being corrected by someone who knows more about this than I do.

This matches my experiences and my knowledge of chemistry. It's inadvisable to store ph pens with electrodes dry, including the cheap ones. I don't have KCl, but I do have 7 reference solution, so that's what I'm storing them in. I also have two meters, so I'm fairly certain I can hone in on the right ph by averaging the two. I just need it around 6.2 - 6.8, anyway.

I'm sure I will be buying a better ph pen with time, but for my first ever grow, I'm fine with just two cheap pens.

 

[GeorgeCloney]

so,
For those taking notes (not ).
As Olderfart said...cheap is questionable.
$50 gets you a real PH pen to grow like the big boys.
In our next lesson, for some...
Will be talk about how to read and ACTUALLY use a Ph pen.
And my sarcasm comes from people who buy shit to look good...and post crap, but don't have a (capital F goes here),...about hydrogen ions.
Google is your friend..
Google PH...and Google Hydrogen Ions...

If you feel offended by my comment, its because 90% of the people on this site look for a quick fix to problems.

On the other hand"...
About 20 people on this site are either biologists or horticulturalists so you may want to take some notes .

This divides the....ok I'm listening crowd...
From those that will ( watch...my prediction!)...yo Adrienne...Crowd....

@Olderfart
Excellent post...
Very well explained...
I repeat, some don't have a F'ing clue what you're talking about...

 

[thebombhaha]

so,
For those taking notes (not ).
As Olderfart said...cheap is questionable.
$50 gets you a real PH pen to grow like the big boys.
In our next lesson, for some...
Will be talk about how to read and ACTUALLY use a Ph pen.
And my sarcasm comes from people who buy shit to look good...and post crap, but don't have a (capital F goes here),...about hydrogen ions.
Google is your friend..
Google PH...and Google Hydrogen Ions...

If you feel offended by my comment, its because 90% of the people on this site look for a quick fix to problems.

On the other hand"...
About 20 people on this site are either biologists or horticulturalists so you may want to take some notes .

This divides the....ok I'm listening crowd...
From those that will ( watch...my prediction!)...yo Adrienne...Crowd....

@Olderfart
Excellent post...
Very well explained...
I repeat, some don't have a F'ing clue what you're talking about...

I have basic information. I don't know if that counts as a clue or not as it pertains to this. I currently adjust my pH by the use of pH Down being that my pH is around a 9 by default. I need around 20ml of pH Down per 3g solution to get it to plant level. My tap is horrible. I use a droplet tester kit to be sure about this and not cause detrimental problems for the plants. I don't know if that's the best or most accurate method to measure pH, but it's what I've done for two grows now ever since I was told of it. My cheap meters never calibrated or worked in general before my first grow ever. Both of the cheap EC and pH meters from eBay I bought together were complete trash. So, I had to go with what I was told and abandoned the meters. I haven't been able to test ppm. I would like to but I need a reliable meter for this. I've learned how to dose pH Down in my solution over time with the droplets. I want to clarify something regarding pH testing since I'm semi-new to growing in general. I'm in the middle of my second grow and this time I'm doing autos. I did 5 photos veg'd for 3 months before for my first grow. My question is if the droplet kits color scheme is entirely accurate? Would you see more accurate results with a Bluelab meter for example?

 

[GeorgeCloney]

I have basic information. I don't know if that counts as a clue or not as it pertains to this. I currently adjust my pH by the use of pH Down being that my pH is around a 9 by default. I need around 20ml of pH Down per 3g solution to get it to plant level. My tap is horrible. I use a droplet tester kit to be sure about this and not cause detrimental problems for the plants. I don't know if that's the best or most accurate method to measure pH, but it's what I've done for two grows now ever since I was told of it. My cheap meters never calibrated or worked in general before my first grow ever. Both of the cheap EC and pH meters from eBay I bought together were complete trash. So, I had to go with what I was told and abandoned the meters. I haven't been able to test ppm. I would like to but I need a reliable meter for this. I've learned how to dose pH Down in my solution over time with the droplets. I want to clarify something regarding pH testing since I'm semi-new to growing in general. I'm in the middle of my second grow and this time I'm doing autos. I did 5 photos veg'd for 3 months before for my first grow. My question is if the droplet kits color scheme is entirely accurate? Would you see more accurate results with a Bluelab meter for example?

I think your last statement/question is very good.
Lets consider 3 possible ways to read PH and go from there....
1)...do nothing( no explanation required).
2) use inexpensive tools and trust them for accuracy.
3) Use more expensive tools that give you true readings and PREDICTABLE correction for PH.
...
@thebombhaha
Your approach albeit intelligent has a problem.
what if the base PH changes?...now what?

I would like to add the following comment

If you're concerned about ANY plant ailment, start by looking at your feed AND runoff PH...
( being an A Hole comes naturally to me so please...laugh and carry on..)...
read your bloody ph runoff...
Google ph runoff...

and some come back to this post and now say...
Holy (F),....so my problem isn't calcium lockout,...its because my ph is out of whack at the roots.
Now, you're learning something
Not just taking a fish for supper but actually learning how to fish...
now yu'r talk'n...

 

[Olderfart]

I have basic information. I don't know if that counts as a clue or not as it pertains to this. I currently adjust my pH by the use of pH Down being that my pH is around a 9 by default. I need around 20ml of pH Down per 3g solution to get it to plant level. My tap is horrible. I use a droplet tester kit to be sure about this and not cause detrimental problems for the plants. I don't know if that's the best or most accurate method to measure pH, but it's what I've done for two grows now ever since I was told of it. My cheap meters never calibrated or worked in general before my first grow ever. Both of the cheap EC and pH meters from eBay I bought together were complete trash. So, I had to go with what I was told and abandoned the meters. I haven't been able to test ppm. I would like to but I need a reliable meter for this. I've learned how to dose pH Down in my solution over time with the droplets. I want to clarify something regarding pH testing since I'm semi-new to growing in general. I'm in the middle of my second grow and this time I'm doing autos. I did 5 photos veg'd for 3 months before for my first grow. My question is if the droplet kits color scheme is entirely accurate? Would you see more accurate results with a Bluelab meter for example?

The drops are accurate, or perhaps a better term might be consistent. The problem is that the colour scale on the bottle is on paper, and the colour you read is transparent water, so the colors never seem to quite match - interpretation of of the color scale is tricky, and you can waste time and frustration chasing the pH you want. Even after significant effort, the pH measurements most people will achieve with the drops will be less accurate than those taken with a decent meter. Also, a meter just gives you a number, no eyeballing needed. OTOH, with care the drops will usually get you close enough, and they don’t die and leave you stranded. However, if your nute mix is colored, such as Megacrop is, judging the colour scale is even more difficult.

So, choose yer poison - pay for a meter that is both reliable and accurate, use drops that are reliable but not that accurate, or buy a cheap meter that will often be neither.

 

[thebombhaha]

I think your last statement/question is very good.
Lets consider 3 possible ways to read PH and go from there....
1)...do nothing( no explanation required).
2) use inexpensive tools and trust them for accuracy.
3) Use more expensive tools that give you true readings and PREDICTABLE correction for PH.
...
@thebombhaha
Your approach albeit intelligent has a problem.
what if the base PH changes?...now what?

I would like to add the following comment

If you're concerned about ANY plant ailment, start by looking at your feed AND runoff PH...
( being an A Hole comes naturally to me so please...laugh and carry on..)...
read your bloody ph runoff...
Google ph runoff...

and some come back to this post and now say...
Holy (F),....so my problem isn't calcium lockout,...its because my ph is out of whack at the roots.
Now, you're learning something
Not just taking a fish for supper but actually learning how to fish...
now yu'r talk'n...

I hear you. Yeah my intention has always been to learn bro. Keeping an open mind in my opinion is important when it comes to growing. I am by no means saying my way is the best way. Concerning your proposal: If my base pH changes, I would be able to dump the solution out when I test it. The droplet kit goes by a color scheme. The base pH changing doesn't change the fact that I see a color when I test with the kit. When I see the color, I can apply pH Down+pH Up to remedy it. Since I ran out of pH Up, I've been having to seriously be careful of how much pH Down I use. 20ml+2 drops with my eye dropper has given me yellow on the kit(plant level), but beforehand, I fucked up several solutions I made by for example adding 22ml of pH Down to my 3g solution. It showed orange quite a few times and I needed to throw it out since I have no way to raise my pH now.

I can definitely read my pH Runoff with the kit as well. I guess I can do that. My pH being wack at the roots. What does that mean in terms of the solution I feed them? Would that mean that the pH of my solution is fucked up to begin with? I don't know how it goes and I don't know the ins and outs with all of this admittedly. To be clear, I see zero issues with my grow thus far. Perhaps my 1000w light is too close because these autos of mine have grown beyond my expectations vertically. I can't raise the light any more though without going inside the tent. The issue is that my 5' by 5' by 2m long is legit stuffed with 12 autos and they're huge now. I guess making sure the light is at max height before they got too big is a good idea, but I did do my part in raising it a decent amount a number of times throughout this grow. The light was much lower beforehand. I have had the light on super lumens for a while now. There is some tacoing but I can't raise the light any higher with the way I have it setup and how many huge plants are there.

 

[thebombhaha]

The drops are accurate, or perhaps a better term might be consistent. The problem is that the colour scale on the bottle is on paper, and the colour you read is transparent water, so the colors never seem to quite match - interpretation of of the color scale is tricky, and you can waste time and frustration chasing the pH you want. Even after significant effort, the pH measurements most people will achieve with the drops will be less accurate than those taken with a decent meter. Also, a meter just gives you a number, no eyeballing needed. OTOH, with care the drops will usually get you close enough, and they don’t die and leave you stranded. However, if your nute mix is colored, such as Megacrop is, judging the colour scale is even more difficult.

So, choose yer poison - pay for a meter that is both reliable and accurate, use drops that are reliable but not that accurate, or buy a cheap meter that will often be neither.

So true lol. Yeah you summed it up perfectly. I understand the differences now so thank you for that explanation. My nutes are Masterblend. It's a 3 part mix. I don't think they're colored but maybe I'm wrong lol I should be able to tell if it is right? I was actually thinking of trying MC but I had already bought masterblend so I just decided to use that for this run. It saved me so much money and I got dialed into the dosages with weighing out nutes for the first time on a scale. Previously, I used canna coco A+B which ran it's course with me moneywise for my first grow

To add, the droplet kit says to use 3-5 drops to test and I have almost always done 5 drops for the utmost accuracy possible lol